Which of the following is true regarding the command sendmail?

Question

Options

• AWith any MTA, the sendmail command must be run periodically by the cron daemon.
• BWhen using systemd, sendmail is an alias to relayctl.
• CThe sendmail command prints the MTA's queue history of which mails have been sent
• DIt is only available when the sendmail MTA is installed.
• EAll common MTAs, including Postfix and Exim, provide a sendmail command.

• A
  9% (2)
• C
  4% (1)
• E
  87% (20)

Explanation

Option E is correct because sendmail is a standardized interface - virtually all MTAs (Mail Transfer Agents) on Unix/Linux systems implement a /usr/sbin/sendmail binary or symlink that accepts the same basic command-line arguments, allowing scripts and applications to send mail without knowing which MTA is installed underneath. Postfix, Exim, and other common MTAs all provide this compatibility wrapper.

Why the distractors are wrong:

• A is false - sendmail is invoked directly to inject messages, not by cron; cron may trigger queue processing (sendmail -q), but that's distinct.
• B is false - relayctl is an OpenBSD tool for managing relayd; it has nothing to do with sendmail under systemd.
• C is false - sendmail submits or processes mail; queue history isn't its function. Use mailq or postqueue -p to inspect the queue.
• D is false - this is the key misconception; even if the original Sendmail MTA is not installed, Postfix and Exim still provide a /usr/sbin/sendmail command for compatibility.

Memory tip: Think of sendmail as a universal "drop mail here" slot - every MTA builds one so the slot always exists, regardless of which MTA is behind the wall.

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